Radiometeorograph transmitting apparatus



April 1s, 1'944.

C. F. WALLACE RADIOMTEOROGRAPH TRANSMITTING APPARATUS 8 Sheets-Sheet 1Filed April 4. r1940 INVENTOR 'u'. ATTO RN EY April 1s, 1944. C, FWALLACE 2,347,160

RADIOMETEOROGRAPH TRANSMITTING APPARATUS Filed April 4, 1940 l8Sheets-Sheet 2 IgM y INVENTOR HSATTORNl-:Y

April 18, 1.944.

c. F. WALLACE 2,347,160

RADIOMETEOROGRAPH TRANSMITTING APPARATUS Filed April 4, 1940 8Sheets-Sheet 3 xNvENToR April 18, 1944. c z.4 F. WALLACE 2,347,150

RADIQMETEOROGRAPH TRANSMTTING APPARATUS Filed April 4, 1940 8sheets-sheet 4 I 7 I/ l a Y 73 71 INVENTOR April 18, 1944. C, F WALLACEl- 2,347,160

RADIOMETEOROGRAPH TRANSMITTING PPRA'IUSy Filed April 4, 1940 8Sheets-Sheet 5 ffii 14 145 x [140 v INVENTOR M-i ATTORNEY April 18,1944. c. F. WALLACE 2,347,160.

RADIOMETEOROGRAPH TRANSMITTING APPARATUS Filed April 4, 1940 8Sheets-Sheet 6 lNvENToR hu' ATTORNEY April 18, 1944.

C` F. WALLACE RADIOMETEOROGRAPH TRANSMITTING APPARATUS Filed April 4,1940 8 Sheets-Sheet 7 ATTORNEY April 1s, 1944. c. WALLACE 2,347,160

RADIOMETEOROG-RAPH TRANSMTTING APPARATUS Filed April 4, 1940 8Sheets-Sheetl 8 BY ,/rl/T 67 A; ATTORNEY Patented Apr. 18, 1944 UNITEDSTATES PATENT OFFICE RADIOMETEOROGRAPH TRANSMITTING APPARATUSApplication April 4, 1940, Serial No. 327,767

This invention relates to radiometeorograph transmitting apparatus, orradiosondes, that is, to apparatus for the measurement of meteorologicalconditions through various levels of the atmosphere and radiotransmission of the measurements for recording at a receiving station.More specifically, the invention relates to such apparatus of the timeinterval type and intended to be carried by a balloon for thedetermination of the pressure, temperature and humidity values, orconditions, of the atmosphere, and for the wireless transmission of thesame to receiving and recording apparatus at a ground station. Theinvention has been made especially with the idea of providing such anapparatus suitable to be carried by small ;sounding balloons, whetherfree or captive.

The invention aims generally to provide an improved apparatus of thiskind which shall be reliable and accurate in operation, of comparativelylight weight, of comparatively low cost and adapted for mass production,easily calibrated, and capable of being readily repaired and adjusted inthe eld, and having other advantages which will appear from thefollowing description.

Among the special objects of the invention are: to provide aradiometeorograph transmitter having a linear, or straight-line, orother desired calibration; to provide improved pressure,`ternperatureand humidity measuring and transmitting, or circuit-controlling,instruments especially adapted for embodiment in the newradiometeorograph transmitter, but also capable of other uses, and whichpermit of certain portions of the instrument response being spread orreduced in order to achieve greater accuracy of interpretation of therecorded data; to provide for individual calibration and ready repair orreplacement of the several meteorological circuit-controllinginstruments; to provide a unit form of assembly of the power supply, themeteorological circuit-controlling devices and motor, and the radiotransmitter, which together make up the complete radiometeorographtransmitter, and which are each readily replaceable without disturbingthe others; to provide a circuit arrangement and circuit-controllingcontact means whereby the radio transmitter is caused to transmit acontinuous signal during each cycle of operation with momentaryinterruptions for indicating theseveral meteorological conditions; toprovide means for signalling the relative speed of the driving motor ofthe radiorneteorological transmitter as compared to that of the recorderat the receiving station; and to prorent past the humidityandtemperature-responsive elements of a radiometeorograph transmittercarried by a captive balloon.

To these ends, the battery or other power source, the motor andmeteorological circuit-controlling devices, and the radio transmitterare separately cased, forming separate packages adapted to be readilyconnected together or disconnected,

* with provision for establishmentoftlre necessary vide means forproducing an adequate air curelectrical connections by the act ofassembling and connecting the three packages; the meteorologicalcircuit-controlling devices are made as separate individual unitsadapted to be mounted in assembled relation with the motor on a chassisframe or support, and are of novel construction having important newfeatures and advantages, as will appear from the following description;the meteorological units and the motor are mounted in a manner to obtainthe required strength and rigidity with a minimum of weight and topermit ready removal and replacement of individual umts and the motor;the radiometeorological transmitter is made to transmit a referencesignal at the beginning. of each cycle of operations and amotorspeed-indicating, or check, signal at the end of each cycle whichmay also serve as an identification signal; al1 as will be hereinafterfully described and speciiically pointed out in the claims.

Before proceeding further with a description of the new apparatus,systems and apparatus of the prior art will be briefly discussed.

Radiometeorographs, also known as radiosondes, have been used quiteextensively both in this country and abroad during the last iive or sixyears, but until recently they have been more or less of an experimentalnature, and designs representative of the ideas of the experimentors inthis field are not adaptable to commercial production or to repair orrecalibration by average personnel in the field.

The known radiometeorograph transmitters can be roughly classified intotwo major groups@ i. e., those which depend on the change in atmosphericpressure during ascension for the operation of the measuring andtransmitting apparatus, and those which employ some form of clockworkfor such purpose. Both of the above-mentioned groups can be furthersub-divided into two categories, i. e., those which transmit a radio oraudio frequency that is variable with the position of the meteorologicalelements, and those employing a time interval transmitter which utilizesthe time between impulses as a measure of the position of themeteorological elements.

In the rst-mentioned class, i. e., the type of equipment transmittingvariable frequencies, one form of apparatus introduces resistance intothe circuit of the audio oscillator which modulates the radiotransmitter, the amount of resistance introduced being determined by theposition or condition of the barometric, humidity and temperatureelements. In another form of apparatus of this general type, thesensitive elements position the plate of a condenser which in turndetermines the frequency of the radio carrier wave and, as a result, thevariations in radio frequency from a predetermined index value determinethe measurements.

Apparatus of the types just described are not particularly accurate dueto the numerous variables encountered which tend to influence thefrequency of the transmitted signal. To mention but a few, variations inlament and plate battery voltages react on the frequency, temperaturechanges produce adverse effects; and errors in the frequency determiningapparatus at the receiving point often further reduce accuracy.

The use of frequency sensitive radiometeorograph transmitters usuallyinvolves extensive and costly ground equipment which can be maintainedand serviced only by skilled personnel. Furthermore, the size and weightof this equipment prevents its use as a practical mobile unit.

The motor-operated time interval-radiometeorograph transmitters of theprior art employ, so far as I know, some form of clockwork or othernon-electric means for operating the telemetric circuit-controllingdevices. Due to the' great range in temperature encountered, thesemechanisms vary greatly in speed, and, furthermore, as some form ofescapement is usually necessary, the rotary elements of the apparatushave a stepby-step movement rather than a continuous one, therebypreventing attainment of the high accuracies required for practicalpurposes.

Clockwork mechanisms are also definitely limited in their power outputby space and Weight considerations, and, in addition, their power isfurther reduced and speed variations are accentuated by reason of thefact that the viscosity of lubricants increases at the low temperaturesencountered at high altitudes.

In addition to the above stated disadvantages, these time interval typeinstruments of the prior art also employed various forms of commutatorshaving either radial contact wires extending across a flat rotating discor spirally wound wires wrapped around a small rotating cylinder, andthe contacts positioned by the meteorological elements rubbed againstthese rotating wires in such a manner as to make new points of contacton successive revolutions of the commutator. In order to reducefriction, the contact pressure was necessarily light and thus notpositive in closing, and, in addition, before a contact closure couldresult it was necessary to break down any film or oxide on the new andnot previously used section of the radial or spiral wires, so thatelectrical contact might not coincide with physical contact, and oftenno signal or an improperly timed signal was obtained,

In addition to the contacting diiculties explained above, no provisionwas made in these instruments for correction of the non-linear responseof the various meteorological elements or of the circuit-controllingdevices operated thereby, and as a result individual calibration curveshad to be run for each instrument. Any change or adjustment in the fieldrequired a new calibration and the laying out of new calibration curves,and each recorder record had to be corrected and interpreted in terms ofthe characteristic calibration curves of the particularradiometeorograph transmitter used.

A further great fault with practically all radiometeorographtransmitters of the prior art was the fact that linkages, cord and wiredrives, pivoted levers and similar means were used for conveying themovement of the various temperature, pressure and humidity sensitiveelements to the telemetering contactors. Due to the small amount ofmovement available, the sensitivity of the elements to friction, and thefact that play could not be eliminated entirely from such variousco-acting means, a serious error between the actual atmosphericcondition and the readings transmitted by the radiometeorographtransmitter always existed.

Another very great fault with the type of instrument used prior to thepresent invention was due to the form ofconstruction employed whereinthe several pressure, temperature and humidityresponsivecircuit-controlling devices became inherent parts of the completemeteorological transmitter which could be calibrated only as a whole.This prevented interchangeability of individual elements of the completeapparatus in the field, and prevented using methods of calbrationmostsuitable for each particular meteorological circuit-controlling devicebecause of the danger of damaging other such devices not resistant tothe same. l

As the cost of a precision radiometeorograph transmitter isconsiderable, a reward is usually offered for its return with the hopethat the apparatus can be salvaged and used again for other flights. Dueto the form of construction employed prior to the present invention,damage to any one element or even to the radio transmitter or batteryoften necessitated the complete reconstruction and recalibration of theequipment, whereas with my form of units construction any damagedmeteorological circuit-controlling device can be removed in the fieldand a new calibrated device substituted in a few minutes time, and thissame replaceability applies also to the radio transmitter and powersupply.

With my linear, or directly proportional, or otherwisepredetermined-response circuit-controlling devices, exactly the samerange and shape of response curve can be obtained from each one ofdifferent radiometeorograph transmitters, and as a result printedrecorder charts, calibrated directly in terms of pressure, temperatureand humidity can be employed, and data thereon can be used immediatelyupon receipt without any necessity for the application of any correctionfactors whatsoever.

A full understanding of the invention can best be given by a detaileddescription of apparatus embodying the various features of the inventionin the form now considered best, and of certain modiiications thereof,and such a description will now be given in connection with theaccompanying drawings, in which:

Fig. 1 shows a radiometeorograph transmitter according to the inventionas it appears attached to a sounding balloon in flight;

Fig. 2 is a side view and Fig. 3 is a plan view of a radiometeorographtransmitter according to the invention intended especially for use withfree sounding balloons;

Fig. 4 is an end view of a radiometeorograph transmitter of a formadapted especially for use with captive balloons;

Fig. is a view of a characteristic calibration chart illustrating thelinear, or straight line, response obtainable with an apparatusaccording to the invention;

Fig. 6 shows a record chart having thereon a characteristic record ofthe type obtained with a low-altitude-captive-balloon-typeradometeorograph transmitter according to the invention;

Fig. '7 is a similar view showing a characteristic record of the typeobtained with a high-altitude free-flight radiometeorograph transmitteraccording to the invention;

Fig. 8 is a side view of the assembled meteorological units and motor;

Fig. 9 is an end view showing the indexing contacts and cam disc whichappear at the right of Fig. 25;

Fig. 10 is a side view, and Fig. 11 a plan view, of the telemetricbarometric circuit-controlling unit of the apparatus;

Fig. 10a is an enlarged detail sectional View of a part shown in Figs.10 and 11;

Fig. 12 is a side View, and Fig. 13 a plan View on a larger scaleshowing the contact make-andbreak members, or contact assembly, andoperating cam which form part of the barometric unit and of each of theether meteorological unitsyof the apparatus;

Figs. 14 and 15 are, respectively, side and plan views of the telemetrichygrometric circuit-controlling unit of the apparatus;

Figs. 16 and 17 are, respectively, side and plan views of "thetele-metric temperature-controlled circuit-controlling unit 0f theapparatus;

Figs. 18 and 19 are, respectively, side and .plan views of a contactassembly for use in the meteorological units of the apparatus when thesignals are to be transmitted as short radio impulses rather than asinterruptions in a continuous signal;

Fig. 20 is a view of an electric motor suitable for use as part of anapparatus according to the invention, the view being taken lookingtoward the plate on which the motor parts are mounted;

Fig. 21 is an edge View of the motor looking from the right of Fig. 20;

Fig. 22 is a detail view on a somewhat larger scale showing the motorshaft and governor rod carried thereby;

Fig. 23 is a further enlarged detail view partly in section of thebearing member for one end of the motor shaft;

Fig. 24 is a sectional View on the scale of Fig. 23 of the bearingmember for the other end of the motor shaft;

Figs. 25 and 26 are, respectively, side and edge views showing thereduction gears of the motor;

Fig. 27 is a wiring diagram of a complete apparatus according to theinvention for transmitting signals as momentary interruptions in acontinuous signal; and

Fig. 28 is a similar view illustrating a modified form of the apparatusfor transmitting the signals by short radio impulses and employing thecontacting devices of Figs. 18 and 19.

Use of the new apparatus and its general appearance in flight whencarried by a free balloon are illustrated by Fig. 1, which shows theradiometeorograph transmitter a suspended by cords b from a smallparachute c, which in turn is suspended by a cord d from a small freeballoon e inflated to a predetermined degree with a light gas such ashelium or hydrogen, an antenna l extending downward from the radiotransmitter casing. A receiving apparatus g and operator at the groundstation are also indicated.

The new radiometeorograph transmitter comprises three principaldivisions or parts housed in three separate containers I0, II and I2,batteries forming the power source being in container l0, themeteorological transmitter comprising the driving motor andmeteorological circuit-controlling devices, or telemetering`transmitters, and indexing circuit-controlling device in container II,and the radio transmitter in container I2, the three containers withtheir enclosed apparatus parts being assembled and secured together asshown in Figs. 2 and 3 to form the com- .plete radiometeorographtransmitter. The apparatus parts within the containers are somewhatdiagrammatically indicated in Figs. 2 and 3. This unit type ofconstruction has the advantage that in the event of damage to any unit,the damaged unit may easily and quickly be disconnected and a new likeunit substituted. Also, the radio transmitter can be rapidlyinterchanged with one designed for operation on a Widely differentfrequency or having some other diierent characteristic, and other typesof power supplies can be readily attached, for instance, the enginegenerator apparatus covered by myl copending application Serial No.317,635, led February 7, 1940, when greater power or length of operatingperiod is desired.

Each of the containers III, II and I2 is made of corrugated paper, balsawood, or other suitable light-weight heat-insulating material, and theyare most desirably coated on the outside with a glossy white waterproofpaint or else made of a suitable light-reflecting material, so as tolimit the absorption of heat from the suns rays. Metallic coatings suchas aluminum paint or foil can also be used, but in such case thecontainer I2, which houses the radio transmitter, must be of such sizeand shape as to prevent any undesirable reaction due to the presence ofthis metallic coating adjacent to parts of the radio transmittingequipment carrying radio frequency currents. The central container IIhas Ventilating openings in its top and bottom Walls to permit freepassage of air through the casing chamber so that the containedhumidityand temperaturesensitive elements are continuously laved by anair current owing through the chamber while the instrument is ascending.The initial rate of ascension is usually in the neighborhood of 600 feetper minute. In order to prevent erroneous readings due to impingement ofsuns rays on the meteorological elements, a' sun shield is providedformed by a tube I3 the lower slightly reduced end of which extendsthrough the opening in the top wall of the container and which isfastened in place by suitable means such as cords I4 and wrap-aroundtabs I5. A tube of sufficient length serves as a suitable solar shieldexcept when the sun is directly overhead, and avoids interference withthe desired air flow through the chamber; but -additional sun-shieldingmeans may be .provided as may be required.

A small antenna insulator I6 of suitable radio frequency insulatingmaterial, such as that commercially known as Isolantite, is set into thebottom` wall of the container I2 which houses the radio transmitter, andcarries a terminalt clamp Il for securing the end of an antenna wire I8.The antenna I8 is preferably made of copperclad or copper plated steelwire of small diameter so that it will not become permanently distortedif it should hit some object when the balloon is launched. For theapparatus shown, it should be a half-wave antenna, but any suitable typeof antenna may be used depending on the type of radio transmitter andmethod of antenna coupling used.

The three containers are secured together, with container Il) on oneside and container I2 on the opposite side of container I I, byconnecting means adapted to permit of ready separation of the containersand ready connection thereof in aS- sembled relation. Most desirably,cords 28 and 'wrap-around tabs 2l are used for this purpose,

the tabs being located preferably near the edges of the top and bottomwalls of the containers as appears in Figs. 2 and 3. The centralcontainer I I has set in its opposite side walls against whichcontainers I and I2 are assembled a light-weight connecting plug 22 inone wall and a light-weight socket 23 in the other, and the inner sidewall of container l0 is provided with a complementary socket 24 forcoacting with the plug 22 and the inner side wall of container I2 has aplug 25 for ccacting with the socket 23, to make the necessaryelectrical connections between the apparatus parts housed in the threecontainers.

The bridle cords bare fastened to reinforced parts of containers I0 andI2 so that the complete radio-meteorograph transmitter is therebysuspended and held in the proper position in night. Instead of thesimple arrangement shown, it is preferable under certain conditions tohave a swivel connection between the transmitter and the parachute inthe customary way so that any tendency of air ciu-rents to rotate thetransmitter will not result in snarling the support cords whereby properopening of the parachute might be prevented.

While the mere provision of openings for permitting air iow through thecentral container II is all that is necessary for obtaining a continuousair current through the container chamber in the relatively smallradiometeorograph transmitters intended to be attached to free bailoons,it is desirable to provide means for inducing the desired air iiow intransmitters intended to be carried by captive balloons in order toassure adequate ventilation of the temperature and humidity elements.For creating the desired air current through the container which housessuch elements in transmitters intended to be carried by captiveballoons, an arrangement such as shown in Fig. 4 is most desirablyprovided. As shown by dotted lines in this gure, a fan 26 is provided inthe air tube I3 driven by a small motor 21 receiving its current fromthe battery in the casing ID and serves to create an upward draft of airthrough the metering chamber and out through the air spaces under theedge of a conical cap 28 which also provides an effective sun shield atall times and prevents the entrance of rain or snow.

In radiometeorograph transmitters according to the invention intendedfor use with captive balloons, it is desirable to use temperature andpressure elements of somewhat larger` size so that a relatively largemovement of the telemetering contacts is obtained over the more limitedpressure and temperature ranges encountered. It is also often desirablein the instruments for captive balloon use to employ larger radiotransmitting apparatus and larger power supplies so that much longerperiods of operation may be ob- Ill) tained than with the high altitudedevices made for free balloons which usually are in flight, for not morethan about ninety minutes at a time. Even though the larger radiotransmitters, and especially the larger batteries or other power source,means greater weight, this is permissible because of the greater liftingpower of the captive balloons used for this type of service.

The power source housed in container I0 for supplying current for theradio transmitter and the driving motor may consist of a 6-volt lament,cr A, battery and a -volt plate, or B battery. Radiometeorographtransmitters for free flight balloons usually have a comparatively lowpowered radio transmitter, and for such transmitters batteries of theprimary, or dry cell, type are suitable. When higher powered radiotransmitters are used, or greater duration of ight required, and whenthe apparatus is of the continuous signal type, miniature A and Bbatteries of the secondary, or storage cell, type may be used, andbatteries of this type are shown in Figs. 27 and 28.

The apparatus parts housed in container Il are shown in Fig. 8, theseparts being the motor enclosed within a protecting housing 3U ofaluminum or other suitable light material, the pressure-responsivetelemetering transmitter unit 3|, the humidity-responsive telemeteringtransmitter unit 32, the temperature-responsive telemetering transmitterunit 33, and an indexing circuitcontrolling device 34, The pressure,humidity and temperature units are mounted side by side in achannel-shapedchassis or support bracket 35 and are separatelydetachable therefrom. The

motor parts, including the housing 30, are carried by a plate 3S whichis detachably secured to the end of the chassis 35. The parts of theindexing circuit-controlling device 34 are mounted on the frame of thepressure unit. 'Ihe pressure, humidity and temperature units are eachentirely self-contained and complete, having a driving connection to acommon motor-driven shaft and electrical connections from their contactmembers to the radio transmitter and to the battery, and, beingseparately and detachably mounted on the chassis, each unit may be takenaway from the others for calibration and any damaged unit may readily beremoved and replaced by a like unit.

The pressure unit 3I is shown in side and plan View on an enlarged scaleby Figs. l0 and 11. All the operating parts of the unit are carried by aframe having two parallel spaced side plates 40 and 4I each of which hasat one end a ange 42 with tapped screw holes for attachment to thechassis 35. The unit comprises a pressure element, or capsule, 43, ofmore or less conventional construction consisting of two somewhat dishedcorrugated diaphragms of metal of high elastic limit joined together at.their peripheries to form a chamber from which air is evacuated. Undercertain conditions, it is considered best to evacuate this chamber to ashigh a degree as possible, but under other conditions, it is desirablethat a small residuum of air be left in the chamber for temperaturecompensating purposes. The pressure capsule is rigidly secured by meansof a stud 44 extending from one side of the capsule to one arm 45a of aU-shaped support member 45 the two arms of which extend on either sideof the capsule and the other arm 45h of which carries a shaft 46 whichextends between the nanges of a plate 4'! set between the side plates 40and 4I, the shaft being pivoted on the ends of clamping screws 4Bscrewed into threaded openings in the flanges of plate 41, as shown inFig. 10a. The flanged plate 41 is adjustable longitudinally between theside plates 40 and 4| to which it is normally clamped by the screws 48and screws 49, these screws extending through short slots 50 in the sideplates to permit such longitudinal adjustment of the flanged plate 41when the clamping screws are loosened. A transmitter arm i which carriesat its outer end the circuit-controlling contact assembly is pivotallyconnected at its inner or fulcrum end to the arm 4517 of the U-shapedmember 45 by -a transversely-extending thin plate or leaf of springmetal 52, which may be beryllium-copper, Phosphor-bronze, or the like,the opposite edges of this pivot plate being set in transverse slotsin`the end of the arm ofthe U-shaped member and in the end of-thetrans emitter arm and being secured therein by solder. The transmitter arm isalso similarly connected to a stud 53 extending from the opposite sideof the capsule 43 from that from which the stud 44 extends by a similarthin plate or leaf spring metal 54 extending into and soldered intransverse slots in said stud and in the transmitter arm.

A spring 55 formed of a U-shaped spring wire having its bight engaged ina notch 56 in the U-shaped member 45 and its two legs extending over theshaft 46 and into engagement with the inner edge of plate 41 yieldablyurges the mem-` member is limited by an adjusting screw 51.

By turning the screw 51 in one direction, the U-shaped member ispermitted to swing in anticlockwise direction under tension of itsspring 55, and when the screw is rotated in the opposite direction, adownward movement of the right hand end of the U-shaped member as viewedin Fig. 11 results.

A cam 60 of Bakelite or other non-conducting wear-resistant materialmounted fast on a shaft 6i journalled in the side plates 40 and 4l anddriven by means o f a gear 62 operates the contact assembly carried bythe transmitter arm 5l to open momentarily a normally closed circuit tothe radio transmitter at a time during each revolution of shaft 6Idependent on the position of the transmitter arm 5I as determined by thecondition of the pressure capsule 43 in response to the atmosphericpressure.

The circuit-controlling contact members, constituting the contactassembly, carried by the transmitter arm 5I of the pressure unit, areshown on a larger scale by Figs. 12 and 13. Each of the other twometeorological units has a like contact assembly. The transmitter arm 5|of the pressure unit is extended to form, and the corresponding memberof the other units, carries, or is extended to form, a support bar orstrip 19, and on this support bar at a suitable distance from its outerend is mounted a plate 1l of insulating material, such as Bakelite, andbetween this plate and a similar plate 12 is secured the flattened endof a spring'contact rod or wire 13, preferably of silver or other raremetal, the free end of which is bent transversely and then over to forma U, as indicated at 14, thus providing in eifect two spaced contactterminals. Another similar contact rod or wire 15 has its flattened endclamped between the insulating plate 12 and a third plate 16 ofinsulating material, the three plates being clamped together by means ofscrews 11, the contact rods thus being adjustable longitudinally onloosening the screws 11. The free end of this second contact rod extendsthrough the U-form end of the rod 13 and beyond this U-end is bent atright angles to form a cam-engaging end 18.

The two contact rods 13 and 15 are tensioned so that when not engaged bythe cam B0 the end of rod 13 rests on a piece of insulating material 19secured to the upper side of the support bar 10 and the end of rod 15rests on the lower arm of the U-end of rod 13 as viewed in Fig. 13. Whenthe cam 50 on its revolution makes contact with the cam-engaging end 18of the contact rod 15, the rod 15 is raised out of engagement with thelower arm of the U-form end of the rod 13, thus opening the circuit atthis point, and then, as the revolution of the camcontinues,therod-15israisedfurther intoA engagement with the upper arm of theU-form end of rod 13, thus re-establishing contact between the twocontact rods, and thereafter rods 13 and 15 are moved together until thehigh point of the cam passes beyond the end 18 of rod 15, whereupon therods return to their position of rest on the end of the support bar.Contact between the two rods 13 and 15 is thus interrupted for a veryshort period, say, a second or i less, during each revolution i" tHe"operating cam 60, while the rod 15 is moved by the cam from the lowerarm to the upper arm of the U-form end of rod 13. Therefore, thetransmitter circuit will be interrupted at some time during the rotationof the cam, and thetime in each rotation of the cam, that is, theposition in time in each successive cycle of the operation of thedevice, will depend on the angular motion imparted to the support bar 19by the pressure, humidity or temperature element, as the case may be.

Going back, now, to the pressure unit shown in Figs. 10 and 11, if themovement imparted to the transmitter arm 5I, and as a result to thecontact assembly carried thereby, is non-linear, that is, notproportional to changes in the atmospheric pressure as measured by thepressure capsule 43, the contour of the cam 60 of this unit can be soshaped as to produce time interval increments that are linear ordirectly proportional to changes of atmospheric pressure. Also, thecontour of the operating cam '60 can be shaped to produce non-uniformtime interval increments. thereby permitting certain portions of thepressure range to be spread out on the recorder` chart in order topermit their more accurate study on the chart. For examplefwith aconstant rate of ascent the change in pressure near the ground will bemuch more rapid than at high altitudes. A pressure change of 50millimeters of mercury at sea level represents alchange in altitudeapproximating 1870 feet; whereas a change of 50 millimeters at analtitude where the pressure is 200 millimeters of mercury represents achange in altitude of over 6000 feet; so that it would sometimes 'be ofadvantage to deorm the periphery of the cam 6I) to cause a given rangeof the lower pressures to spread over a greater portion of the total camrevolution than a similar range at the higher pressures.

By loosening the clamping screws 48 and 49 and adjusting the anged plate41 longitudinally, thereby adjusting the transmitter arm 5l and thecontact assembly carried thereby longitudinally with relation to the camB2, and making a compensating longitudinal adjustment of the contact rod15 to keep its bent contact end 13 ln proper position with relation tothe cam, the magnitude of movement imparted to the transmitter arm andcontact assembly by the barometric capsule for a given pressure changemay be adjustably varied, thereby adjustably varying the spread on therecorder chart of the data marking indicating such pressure change. Bysuch adjustment, therefore, variations in the expansion and contractionof the barometric capsule resulting from difference in the materials orconstruction of the capsule can be compensated for, and the movement ofthe transmitter arm can be maintained within any desired predeterminedrange in all instruments.

Angular adjustment of the transmitter arm by means of the adjustingscrew 51 determines the by the cam for any condition of the `barometriccapsule, that is, for any atmospheric pressure. This adjustment,therefore, determines the time in each cycle of operations at which thepressure signals are transmitted, and therefore determines the positionof the range of pressure markings on the chart of the recordinginstrument.

Therefore, by longitudinal adjustment of the transmitter arm andcompensating adjustment of the contact rod 15, the horizontal spread ofthe data markings on the recorder chart may be adjusted to agree withthe spacing of the printed pressure lines of the chart, and by theangular adjustment of the transmitter arm, the exact location on thechart of the data markings may be adjusted to the printed chartmarkings. The instrument may thus be readily calibrated so that itstransmissions will result in a record which may be read directly withoutresort to any correction factors whatever. By providing cams havingpredetermined effective peripheral lengths, the pressure recordings,(and the same is true for temperature and humidity recordings as willappear), may be located in denite zones on the recorder chart Withoutoverlap, as shown, for example, by Fig. 6, which indicates a typicalrecord as made by a low altitude instrument, or, as a further example,the temperature and pressure readings may be spread over a major portionof the recorder chart and the humidity readings conned to a minorportion as illustrated by the typical high altitude record of Fig. '1.The straight line calibration curves obtainable with the new pressure,humidity and temperature units are illustrated by Fig. 5.

The humidity-responsive telemetering transmitter unit 32 of theapparatus illustrated is shown in side and bottom plan views in Figs. 14and l5. In this unit the operating parts, as in the pressure unit, arecarried by a frame having two side plates 80 and 8| which have flanges32 at one end with screw holes for attachment to the chassis 35. Thehumidity-sensitive element 83 is of the Well known hair type consistingof a multiplicity of hairs extending in close arrangement side by sideand held at the ends by metal clamps. This hair element is pivotallyconnected at one end to one arm of an L-shaped support member 84 and atits other end to the end of a rod 85. The rod 85 extends from and isrigidly secured to a cross-member 86, which extends between the sideplates 80 and 8| and is secured thereto and clamped against turning byclamping screws 81. The rod 85 is thus adjustable for varying theinitial position of the hygrometer element by loosening the screws 81and then tightening them when a desired adjustment has been made.

The connection of the upper end of the rod 85 to the metal clamp of thehygrometer element is by means of an adjusting screw 09 which extendsthrough an eye in the end of the rod and screws into the flanged end ofa plate extending from the clamp 80. By means of this screw, veryaccurate adjustment may be made of the position of the hair element forthe purpose of adjusting the contact assembly of this unit with relationto its operating cam in a manner similar to that resulting fromadjustment ci the screw 51 of the pressure unit.

'Ihe L-shaped member 84 is carried by a shaft S0, which is journalled inthe side plates 80 and 8|, and a coiled spring 9|, which has its innerend hooked over the lower arm of the L-shaped member as viewed in Fig.15 and its outer end hooked over the upper side of the side plate 8|,constantly urges the L-shaped. member to rotate in a clockwise directionas viewed in Fig. 15 and thereby to maintain the hairs of the hygrometerelement under constant tension. The lower or longitudinally extendingarm of the L-shaped member 84 carries at its outer end a contactassembly similar to that of the pressure unit and as shown by Figs. 12and 13 and which is operated by an insulated cam 92 on a shaft 93journaled in the side plates 80 and 8| and driven througha gear 94. Asthe contactassembly is the same as that of the pressure unit and asshown in Figs. 12 and 13 and is operated in the same manner by its camto open the circuit momentarily at a time during each revolution of thecam determined by the hygrometer unit, it need not be further described.It will be understood that the L-shaped member 84 will be given a slightangular movement as the hygrometer elements expands or contracts withchanges in the amount of moisture present in the atmosphere, thismovement of the member 84 causing the cam-engaging end 18 of the contactrod 15 supported by the bar 10 to move toward or from the cam 92.

The temperature-responsive unit 33 of the apparatus is shown in Figs` 16and 17. As before, the operative parts of this unit are carried by aframe having two spaced side plates |00 and |0| which have anges |02with screw holes therein for attachment of the unit to the chassis 35.The temperature-responsive element |03 of this unit as shown is a thinbi-metal plate or strip rigidly connected at one end to a hinged anged,or U-shaped, member |04, the edge of the bimetal strip being enteredinto slots in the two flanges of the member |04 and soldered therein. Byconnecting the bi-meta1 strip to its supporting member in this way,there is a minimum amount of thermal contact between the two. This isdesirable for obtaining rapid response to temperature changes, as thereis little, if any, ei'ect on the temperature-sensitive element by heatstored in the somewhat more massive portions of the apparatus. Theopposite end of the bi-metallic strip |03 carries the support bar 10 andother parts of the contact assembly, which, here again, is the same asin the pressure and humidity units and as shown by Figs. 12 and 13, andthe contact assembly is operated by an insulated cam |05 fast on a shaft|05 journaled in the side plates |00 and |0| and driven by a gear |01.Most desirably, the bi-metallic plate or strip |03 has a slot |08extending from its supported or heel end and for a good part of itslength for the purpose of equalizing any strains produced by attachmentto the hinged member |04, thereby preventing any buckling effects whichmight otherwise cause an error in the temperature determinations.

The U-shaped member |04 is pivotally mounted between two plates |09 on apivot pin H0, which plates are connected at their lower inner edges by across plate I forming a support memberl which is pivotally mountedbetween the side plates and 0| by means of pivoting and clamping screws||2. By loosening the screws ||2 the plates |09 may be adjustedangularly, thus providing for substantially longitudinal adjustment ofthe temperature-responsive element |03 with relation to the cam |05. Bysuch adjustment of the element and by a compensating adjustment of thecamengaging contact member of the contact assembly to keep it in properposition with relation to the cam, the magnitude of movement imparted tothe contact assembly by the temperature-responsive element for a giventemperature change may be adjustably varied. An adjusting screw I3passes through a clearance hole in the lower part of hinged member |04and through a. compression spring ||4 and threads into the cross plateBy adjusting this screw, the angular position of the hinged member |04and of the temperatureresponsive element and the contact assemblycarried thereby can be varied in thenmanner and for the same purpose asdescribed in connectionTwith the angular adjustment of the member 45 ofthe pressure unit as shown in Figs. and 11.

Referring now again to Figs. 8 and 9, the channel shaped chassis 35provides a rigid support for the three meteorological units and themotor arranged in line, the meteorological units being secured to thechassis by screws extending through the bottom wall of the chassis intothe tapped holes in the end ilanges of the side plates of the units, andthe motor bed plate 36 being secured to outturned ends of the sideflanges of the chassis by screws |2| of which one shows in Fig. 8.

A low speed drive shaft |25, driven by the motor in the housing 30,extends longitudinally of the chassis 35, being journaled at one end inthe motor bed plate 36 and at the other end in the side plate 40 ofpressure unit 3|. The drive shaft carries three pinions |26, |21 and |28which mesh respectively with the gears 62, 94 and |01 of the units 3|,32 and 33. These pinions are secured to shaft |25 by means of springcollets or other adjustable means which permits of their being twined onthe shaft relatively to each other so that the operating cams 50, 92 and|05 of the units 3|, 32 and 33 may be accurately adjusted to set them inthe desired relative angular position and yet which will not yield orslip when shaft |25 is driving the cams. The speed of shaft |25 and therelative size of pinions |26, |21 and |28 and gears 62, 94 and |05 may,for example, be such that the operating cams will be driven to make acomplete rotation in 15 seconds or in seconds, but may. of course, besuch as to give any desired rate of rotation to the cams.

A terminal strip |33 of insulating material is secured to the bottom ofchassis 35 and carries four terminal lugs |3|, |32, |33 and |34. Theterminal lugs |3| and |32 are used for connecting the motor to thebattery or other power source, and the terminal lugs |33 and |34 servefor connecting the contact assemblies of the meteorological units intothe circuit of the radio transmitter. When the apparatus is such thatthe radio transmitter is caused to transmit a continuous signal in whichmomentary interruptions are caused during each cycle of operation by theindexing device and by the several meteorological units, thecircuit-controlling contact assemblies of the meteorological units areof the type shown in Figs. 10 to 17, and are connected in series betweenthe terminal lugs |33 and |34. Each meteorological unit then operates,as above described, to open the circuit momentarily during each cycle ofoperations at a point determined by the meteorological conditionmeasured by the unit. This is also a very short opening of the circuitwhen the cam-engaging end 18 of each contact rod 15 drops off from thehigh point of its operating cam, but these circuit openings are tooshort to be effective to cause a record-producing signal to betransmitted.

Because of the unit form of construction, the meteorological instrumentscan be individually calibrated before assembly, under conditions idealfor each one, and then after calibration be mounted on the chassis 35and secured as stated.

If the apparatus is of the normally open-circuit type by whichintermittent radio impulses determined by the meteorological conditionsare transmitted, the Contact assemblies of the meteorological units ofthe apparatus are connected in parallel instead of in series, theterminal |33 being connected to one contact member of the contactassembly of each of the meteorological units and the other contactmember of each unit being grounded to the chassis, the terminal lug |34,from which connection is made to the radio transmitter, as shown in Fig.28, being also grounded to the chassis. The contact assemblies of themeteorological units of an open circuit apparatus may be of the kindshown by Figs. 18 and 19, such contact assemblies being substituted ineach of the meteorological units in place of the contact assembly shownby Figs. 12 and 13 and in Figs. 10 and 11 and 14 to 17.

Referring now to Figs. 18 and 19, the contact members are carried by asupport bar |40 similar to the support bar 10 of Figs. 12 and 13, andwhich like the support bar 10 either is an extension of or is carried bythe transmitter arm or corresponding part of the meteorological unit,being shown in Figs. 18 and 19'as an extension of the transmitter arm 5|of the pressure unit. This support bar |40 has mounted thereon twoplates |4| of insulating material between which are clamped two springcontact rods |42 and |43 spaced and therefore insulated from each other.The contact rod |42 has abent-over end |44 which extends over the end ofsupport bar |40 and over contact rod |43. Contact rod |43 extendsslightly beyond the bent-over end |44 of rod |42 and has a bent-over end|45 which extends in position to be engaged by the periphery of theoperating cam, marked 62 in these figures, assuming it to be the cam ofthe pressure unit. A small contact piece of rare metal |43 is solderedto the free end of the support bar |40 in position to be engaged by theend |44 of the contact rod |42. From this contact piece groundingconnection is made through the support bar and through other parts ofthe unit to the chassis 35, and thus to terminal lug |34. Contact rod|43 is connected to terminal lug |33. Contact rod |42 is tensioned torest normally on the contact piece |46, and contact4 rod |43` istensioned toward the cam to be normally out of contact with the end |44of rod |42, so that until contact rod |43 is lifted sufficiently by thecam to come into engagement with the end |44 of rod |42, the circuit isopen at this point.

When, however, contact rod |43, as it is moved by its operating cam,comes into engagement with the end |44 of rod |42 which is resting oncontact piece |46, circuit is momentarily closed between rod |43 andsupport bar |43. This closing of the circuit will be only momentarysince by the continued rotation of the cam the rod |43 will be caused tomove rod end |44 out of engagement with the contact piece |45, thusopening the circuit, the time duration of this momentary closing of thecircuit being determined by the yielding of the spring contact rods andthe lift and speed of rotation of the cam. Thus, during each rotation ofits operating cam, each of the meteorological units, having a contactassembly such as shown by Figs. 18 and 19, will cause the radiotransmitter to be momentarily energized to transmit an impulse at a timein the cycle determined by the setting of its cam and themeteorologicalcondition to which the unit is responsive.

By having the contact |46 insulated from the support bar |40, as bymounting it on a plate of insulating material such as the plate 19 ofFig. 13, a completely insulated keying device may be obtained. Theconnections to the same would then be made, one to contact |45 and theother to contact rod |43, thus doing away with the grounding of |46 tothe chassis.

Referring again to Figs, 8 and 9, the indexing circuit-controllingdevice 34 comprises a contact assembly formed by a contact rod |50 and aspring contact rod both held and insulated from each other by a clampingpile |52 carried by a bracket attached to the side plate 40 of thepressure unit 3|, and a cam disc |53 mounted fast on an extended end ofthe cam shaft 6| of the pressure unit. Cam disc |53 has a shortperipheral propjection |54 and has. spaced a short distance from thisprojection in the direction of its rotation, two closely spaced shortperipheral projections |55 and |56. Contact rod |5| is tensioned towardrod |55 and is normally in circuit-closing engagement with the end ofrod |58, and its end beyond the end of rod |53 extends toward theperiphery of the cam disc in position to be engaged and moved by the camprojections |54, |55 and |56 to open the circuit. The two contact rods,as shown in Fig. 8, are connected in series with the contact assembliesof the meteorological units between the terminal lugs |33 and |34.

The cam projections are so positioned on the periphery of the cam disc,and the disc is so positioned angularly with relation to the angularpositions of the cams 55, 92 and |05 of the meteorological units, thatthe projection |54 operates the contact rod |5| to open the circuitmomentarily at the beginning of each cycle of operations and the dualprojections |55 and |55 cause two closely spaced momentary openings ofthe circuit at the end of each cycle after the three meteorologicalunits have made their circuit interruptions. Unlike the interruptionsmade by the meteorological units, the circuit interruptions caused bythe projections on cam disc |53 always occur at predetermined points inthe cycle, and, therefore, if the speed of the motor is constant, thetime interval between the circuit opening movements of contact rod |5|causen` first by projection |54 and then by projections |55 and |56 willbe constant, and the distance between the record markings caused bythese circuit openings will not vary in successive cycles if the speedof the recorder motor is also constant.

In an apparatus designed to produce by signal CII transmission to areceiving station such as hereinafter referred to a record such as shownby Fig. 6, the relative angular settings of the cams 60, 92 and |05 andcam disc |53 are such that in each cycle the pressure unit cam 60operates its Contact device first, then the temperature unit camoperates its contact device, and then the humidity unit cam operates itsContact device. 'I'he projection |54 of cam disc |53 operates just priorto cam 60 of the pressure unit at the lowest end of its range, that is,just before the pressure unit can cause a circuit interruptioncorresponding to the barometric pressure at the start of the flight; andthe dual projections |54 and |55 of cam disc |53 operate just after thehigh end of the range of the temperature unit. The single referencemarkings |51' on the chart are created by the projection |54, and thedouble motor-speed-indicating Vmarks |58eby'the dual projections |55 and|53. If the motor speed is constant, the speed of the recorder motoralso being constant, there will be no change in successive cycles ofoperation in the tirne interval between the instant at which thereference signal caused by the projection |54 creates a mark |51 and theinstant at which the speed indicating signal caused by the projections|55 and |55 creates adouble mark |53, and as a consequence, the doubleline lss will haven@ rinzonri 'displacement but will appear much asshown in Fig. 6. Any increase in the speed of the motor will beindicated by displacement of the double line |58 to the left, and anydecrease in the motor speed will cause line |58 to be displaced to theright.

Under certain conditions, as in a radio meteorological transmitter suchas iilustrated by Fig. 28, in which the meteorological units havenormallyopen-circuit contact assemblies of the kind shown by Figs. 18and 19, it is often desirable to make the cam projection |55 of suicientperipheral length greater than that of projections |55 and |56 so that asignal of suicient duration will be transmitted thereby to enable anoperator at the ground station to keep the radio receiver accuratelytuned to the transmitting apparatus. The reference line will then appearmuch as the line |51 shown in Fig. 7.

When the contact assemblies of the meteorological units are of thenormally open-circuit type as in Figs. 18 and 19, the contact members ofthe contact assembly of the indexing device 34 will be normally out ofengagement and will be put into momentary engagement by the projectionson the cam disc to close the Circuit, and such normally-open-circuitcontact assembly will be connected in parallel with theparallel-connected contact assemblies of the meteorological units asshown in Fig. 28.

The speed check signal may serre as an identifyingsignal, since byproviding the indexing cam disc |53 with the proper peripheralprojections the signal interruptions cr impulses caused thereby may besuch as to produce a check line |58 on the recorder chartof anidentifying character, such as, for example, a line of two dots or ofthree dots or of a dash and dot. Under certain conditions, especially inconnection with military 0perations, it is desirable to operate at thesame time two or more radiometeorograph transmitters using radio carrierfrequencies not greatly sep arated from each other; and in such casethere is always the possibility that the radio transmitters will driftin frequency and possibly cross each other, making it dimcult todetermine which radiometeorograph transmitter is being followed. Theidentifying signal removes this difficulty.

Any suitable light weight motor may be used for driving the shaft |25which operates the telemetering units. I prefer to use a motor of thekind shown in Figs. 20 to 26. This motor is of the general typedisclosed and claimed in the Wallace U. S. Patent No. 1,985,357, and theWallace and MacKay U. S. Patent No. 2,181,841.

As shown by Figs. 20 to 26, the rotor |60 of the motor is a magnethaving a north pole and a south pole, which is most desirably circularin order to secure dynamic balance and strain, and thereby greater speedof rotation than if of the bar magnet type, and which is best made froma magnetic alloy commercially known as Alnico in view of this alloyshigh magnetic flux density:i and high resistance to demagnitization fromstray fields or vibratory effects. Due to these improved magneticproperties, a smaller and lighter weight rotor can be used than if therotor were made of other magnetic materials of which I have knowledge.

The rotor extends into a magnetic field created wire mounted to one sideof the rotor shaft |62.

Obviously, for a more efficient though slightly heavier motor, twostator windings might be employed as shown in the above cited U. S.patents.

The rotor shaft is made from a hard or tool steel or other suitablemetal, and the rotor is mounted thereon by means of a suitable bushing.-As shown by Fig. 22, the shaft has reduced -ends which are journaled intwo-piece jeweled bearings carried by holders |63 and |64 which aremounted one in the motor bed plate 36 and the other in a flange of aframe |65 of brass or aluminum or other suitable material which issecured to and extends out at right angles from the motor bed plate 36.The bearing holder |64 is seated in the bed plate, and the holder |63 isadjustably mounted in the flange of the frame. The bearings are of usualform, each having a ring stone |66 and a cap stone |61 which may be madefrom synthetic sapphire, ruby or garnet, or other suitable material, andthe bearings are set so as to permit of sufficient longitudinal movementof the shaft to obviate possibility of binding of the shaft which mightotherwise result from unequal expansion or contraction of the shaft andthe supporting frame when extreme changes in tem.-

perature are encountered. Due to the low temperatur-es at which thesemotors have to operate, only a very small amount of lubrication, or nolubrication at all, is permissible, and bearings of the type illustratedhave been found most advantageous for this condition of service. Thebearing holders may be made of brass or other suitable material, and thestones maybe secured in position by a slight rolling or swaging over ofthe holder material about the outer edges of the ring stones. To providefor adjustment of the bearing holder |63, it has a threaded shank orbody which screws through a tapped hole in the frame and through atapped hole in a flat spring |68. the ends of which bear against theoutside of the frame and which acts as a locking member to maintain thebearing member in fixed position against the effects of vibration. Thestator coil |6| is secured to the frame |65 by means of clamping stripsof Bakelite or other insulating material held by screws |69.

The commutating contacts of the motor are provided by a movable contactmember |10 and a stationary, or substantially stationary, contact memberl1 I. The movable contact member |10 is formed by a piece of springsilver wire secured to the frame |65 by a grounding screw |12 and thefree end of which extends past an eccentric, or cam, portion |13 of therotor shaft and is tensioned to bear against this eccentric portion ofthe shaft during at least a part of the revolution of the shaft. Thestationary contact member |1| is formed by a strip of spring silver oneend of which is insulated from the frame and secured by a screw |14 andthe free end of which extends in position to be engaged by the end ofthe movable contact member when the latter is moved by the eccentricpart of the rotor shaft. This contact strip |1| is tensioned toward theend of the movable contact wire and is held in position for engagementby the movable contact by an adjusting screw |15 carried by a stationarymetal strip |16 also secured by the screw |15 and insulated from theframe. As the rotor shaft rotates, therefore, intermittent contact willbe made between the movable and stationary contact members, and, theeccentric portion |13 of the shaft being properly positioned angularlyin relation to the plane of the stator coil and the magnetic axis of themagnet, rotation of the rotor will result. If the motor is intended torun for a long time without cleaning of the contacts, it is desirable,in order to reduce or eliminate sparking at the contacts |10 and |1|, tohave the contacts shunted with a small condenser resistor unit or toprovide a high resistance in parallel with the coil 16|.

The rotor shaft carries a small pinion |11 from which through a suitabletrain of reduction gearing |13 the driving shaft |25 is driven at thedesired speed, to provide, for instance, transmission of two cycles ofmeterological data per minute. The motor may, of course, be operated atdifferent speeds, or different gear ratios may be employed, to providefor any desired speed of rotation of the driving shaft |25.

The circuit of the motor is substantially the same as that shown for themotor mechanisms in the patents cited above, the current through themotor owing in a circuit as follows: from a connection on a plate |19 ofinsulating material to and through the coil |6|, thence to the frame |65and then through the movable contact |10 5 to the stationary contact|1|, and then back to the opposite side of the source.

Instead of a circuit interrupting governor means, it has been found moredesirable in many cases to use a governor of the friction type as shownin order to insure very accurate speed regulation under the temperaturevariations to which the motor is subjected in use and which result invarying the ohmic resistance of the stator field winding and in loweringthe battery voltages to some extent. A governor of this type alsoinsures a somewhat smoother action, and, furthermore, reduces weight andspace requirements. This governor as shown comprises a rod of brass orother suitable material mounted fast on the rotor shaft to extend atright angles therefrom in both directions, a weight |86 slidably mountedon one end of the rod and under tension to move toward the shaft |62 bya coil spring |81, and a counterweight |88 which is longitudinallyadjustable on the threaded other end portion 'of the rod. One end of thespring |81 is screwed onto a threaded boss on the inner end of theweight |85. The other end of the spring is reduced and engages athreaded portion of the rod |85. This small end of the spring may thusbe adjusted longitudinally of the rod for adjustably varying the pull ofthe spring on the weight. The outer end of the weight |86 carries asmall contact piece or pad |89 of suitable friction material, such ascork or leather, which may be set in and cemented or otherwise securedin a recess in the outer end of the weight.

As the shaft rotates, centrifugal force tends to cause the weight |85 tomove outward on the rod |85, this movement being resisted by the spring|81 and limited by a coacting friction ring |90 which is mounted in theframe |65 and positioned concentric with the axis of the motor shaft andin the plane of movement of the weight |85. The ring has a smooth innersurface, and for lightness is desirably made of thin brass or othersuitable metal reinforced by having flanged edges, as appears from Fig.21. Wh-en the motor reaches a certain speed, determined by theadjustment of spring |81, the friction-shod end of weight |86 engageswith the inner surface of ring |90, thereby braking the motor and byconventional governor action maintaining the motor speed accuratelywithinpredetermined very-l0se limits.

The motor is not provided with any polarizing magnet or other biasingmeans as there is no need to make it self-starting since it runscontinuously while in flight and can be started prior to night eitherdirectly by hand or by imparting a circular motion to the wholeapparatus. A click spring I9I which meshes with the last gear |92 of themotor train |18 serves to prevent reverse movement of the motor due toincorrect connection to the power source or to manual operation. Suchreversal of the motor might result in damage to the telemetering contactassemblies.

This motor is remarkably smooth and continuous in its operation, andpossesses many times the power obtainable from clockwork mechanisms ofcomparable weight, the complete motor weighing only in the neighborhoodof 40 or 50 grams for the radiometeorograph transmitter shown.Furthermore, no lubrication is required for its bearings, and its speedis substantially unaffected by temperature changes. As will behereinafter made apparent, the speed of the driving means is extremelyimportant in all types of time interval metering systems and directlyaffects the accuracy of the results obtained. Motors such as abovedescribed have been found to have speed characteristics superior tosynchronous clock motors operated from socalled commercial power lines.By superior characteristics is meant that over short periods of timetheir speed is much more constant than that obtained over like intervalsfrom commercially energized synchronous motors. It is the cycle to cyclevariation that is important in telemetering, and therefore a slight butuniform drift in speed in one direction or the other is notobjectionable, short and erratic variations in speed being the kindwhich destroy the accuracy of metering.

Referring now to the Wiring diagram of Fig. 27: The three containers I0,II and I2 housing the various parts of the complete radiometeorographtransmitter are indicated by dotted lines in this figure.

A combined storage A" and B battery 200 is shown as in container I0; thecontact assemblies and operating cams of the pressure, humidity andtemperature units and of the indexing device, and the motor and drivingshaft and gears between the shaft and cams are indicated as in containerII; and there isindicated as in container I2 a radio transmitter of theColpitts type, well known in the art of radiometeorography and radiocommunication. As any suitable type of radio transmitting apparatus andcircuits may be used in radiometeorograph transmitters according to theinvention, no description of the radio transmitter shown or of itsoperation is needed for a full understanding of the invention.

The contact assemblies of the meteorological units as indicated in thisfigure are of the closed circuit type, transmitting a continuous signalduring each cycle of operation except for momentary interruptions by themeteorological units and the indexing device, the contact assemblies ofthe meteorological units and of the indexing devices being connected inseries.

The operation of the radiometeorograph transmitter as illustrated bythis ligure is as follows:

Current flows from the positive side of the 6- volt A battery section ofthe combined storage battery 200 through wire 20| and one sleeve of thesocket 24 to the coacting prong of plug 22, and then through a conductor202 to the positive G-volt terminal |32 on the terminal strip |30, andthen by a lead 203 to one side of the driving motor in the housing 30.The other side of the motor is connected by wire 204 to the negative6-volt terminal I3| and then by conductor 205, another prong of the plug22 and coacting sleeve of socket 24 and wire 205 to the negative side ofthe low voltage section of the battery.

Current at potential of 6 volts is also caused to iiow in a circuitstarting at the positive terminal I 32 through conductor 20T, a sleeveand prong of socket 23 and plug 25, and wire 208 to one side of thefilament, or heater, in the vacuum tube 209 of the radio transmitter,and returning from the other side of the filament through conductor 2|0,another prong and sleeve of plug 25 and socket 23, and by conductor 2IIto the negative terminal I 3|.

By these circuit connections from the 6-volt section of the battery, themotor is caused to operate to drive the shaft |25 by which thetelemetering cams 62, 94 and |05 and the indexing cam disc |53 aredriven; and in addition, the filament and cathode of the vacuum tube 209are energized.

Plate voltage is applied to the radio transmitter from the high voltageB battery section as follows: Current ows from the positive side of theB battery through conductor 2|2 and a sleeve and prong of socket 24 andplug 22, and by wire 2 I3 to terminal |33 of the terminal strip |30; andthence by wire 2I4 to spring contact rod I3 of the contact assembly ofthe temperature unit, and, the circuit being normally closed throughthis contact assembly, current flows from its spring contact rod I5through wire 2I5 to the contact assembly of the humidity unit, andthence by wire 2I8 to the contact assembly of the pressure unit, andthence by wire 2I'I to the contact assembly of the indexing device, andthence by wire 2|8 to terminal |34, from which current flows throughwire 2 9, a sleeve and prong of socket 23 and plug 25, and thence by wayof the radio frequency choke coil 228 and wires 22| and 222 to the plateof vacuum tube 209.

The return circuit to the negative side of the B battery is by way ofthe circuit connections before described between the filament of tube209 and the positive side of the A battery to the connecting point 223and thence by conductor 224 to the negative side of the B battery.

The radio transmitter will thus emit electromagnetic waves from itsantenna I8 except when the plate current of vacuum tube 209 ismomentarily interrupted by thek operation of one or another of thecontact assemblies by their cams 60, 92, |05 and |53, and as thesemomentary interruptions caused by the cams of the pressure, humidity andtemperature units bear a signicant time relationship to the positionsassumed by the pressure-, humidityand temperatureresponsive elements ofthese units, and to the speed of the motor, they can serve to actuate orcontrol the sty1us`ofn the recording apparatus ground level frequency ofthe radiometeorograph transmitter does not prevent reception of thesignals. Furthermore, if the frequency of the transmitter continues todrift it is quite easily followed on account of the broad tuning that ischaracteristic of super-regeneration.

For operating the stylus of the recording device, which is usually at ameteorological station, I prefer to employ a relay having both front andback contacts and arranged in a circuit of the type of that of U. S.Patent 2,165,062 of J. R. MacKay. In the systems described in thatpatent the diierential in the rush currents of the superregenerativereceiver, as controlled-byv the carrier wave of the radio transmitter,operate the relay, and as the relay is provided with both front and backcontacts, the stylus may be electrically controlled for operation eitheron a received radio impulse or on the interruptions of at a distantmeteorological"stationdm-the-known-2ufan'"Otherwiseocontnuous--radiorsignahWay.

Fig. 28 is similar to Fig. 2'7 except that it shows a normallyopen-circuit apparatus in which the contact assemblies are of the typeillustrated by Figs. 18 and 19 and the several contact assem blies areconnected in parallel instead of in series as hereinbefore pointed out.In the circuit shown the frame of the motor is most desirably insulatedfrom the chassis as one side of the chassis serves as a connection tothe positive side of the A battery, or else the wiring of the motor andthe circuit of Fig. 28 may be revised so that the frame of the motoracts as its positive terminal. Referring now to Fig. 28, it will be seenthat with exception of the keying circuits controlled by cams 60, 92,|05 and |53, the circuit connections are mostly as in Fig. 27 and havethe same reference numerals. Plate voltage is, however, applied to thevacuum tube 209 as follows: From the positive side of the B section ofbattery 200 current ows through the conductor 225, sleeve of socket 24,prong of plug 22, conductor 225, sleeve of socket 23, prong of plug 25,and through the choke coil 220 and wires 22| and 222 to the plate oftube 209; and the return connection from the negative or cathode side ofthe tube 209 is effected by way of conductor 208, prong of plug 25,sleeve of socket 23, and wire 221 to terminal |34 which is grounded tochassis 35 by lead 228. Current then ows through the chassis and throughthe contact assembly of any one of the meteorological units the contactsof which may be in momentary engagement, or through the contact assemblyof the indexing device when its contacts are in momentary engagement,and thence by wires 235 and 236 to terminal |33, and by conductor 231,prong and sleeve of plug 22 and socket 24, and by conductor 238 to thenegative side of the B section of the battery.

Intermittent radio impulses will thus be emitted by the radiotransmitter as the circuit is momentarily closed by the meteorologicalunits and by the indexing device, the time intervals between thereference signal and the metering signals and the motor speed checksignal indicating the conditions of pressure, humidity and temperatureand also the speed of the motor.

For receiving the radio signals, I prefer to employ what is known as asuper-regenerative receiver because of its great sensitivity at theultra-high frequencies commonly used for radiometeorographictransmission; also, because receivers Vof this type have inherentautomatic volume control properties and are quite broad in their tuningso that small departures from the The particular form of radio receiverand recording device to be used with radio meteorograph transmitters ofthe invention form no part of the invention. It may be pointed out,however, that the type of recording device which it is preferred to usewith the new radiometeorograph transmitter has a synchronizing meanswhereby the pen arm of the recorder immediately returns rapidly to' itsleft hand position ,right after receipt of the double mtorfs'peed checksignal and then is locked at that point until the single referencesignal is received. Receipt of this reference signal releases a latchand permits the pen arm to travel at a constant speed over the surfaceof the chart in a right hand direction, thereby insuring a record thedeparture of which from complete accuracy is dependent upon thenegligible cycle tor cycle relative variations in speed of the motors ofthe transmitter and the receiver, and not on the cumulative variationover the entire period of the flight. Furthermore, in the preferred formof recorder there is provided a means, either manual or automatic, forvarying the speed of the motor which drives the pen arm so vthat ifthere is any departure from the vertical of the line formed by thedouble speed-check signal the motor can be immediately speeded up orslowed down to keep the distance between the reference line and thespeed-check line constant, thereby synchronizing the speed of therecorder motor with the motor of the distant radiometeorographtransmitter.

If the radiometeorograph transmitter is of the form shown by Fig. 4,having a motor-driven fan for maintaining an air current past thehumidity and temperature responsive elements, the fan motor will haveits terminals connected in parallel with the terminals of the drivingmotor so that both operate on the 6-volt battery.

When the meteorological units have contact assemblies of thenormally-closed-circuit type, as shown by Figs. 8 to 17, the instrumentmay be made'to serve for providing indications of wind velocity anddirection, as it can readily be followed with certain types of radiodirection finding apparatus due to its substantially continuous signal.In many cases, however, only indications ol' pressure, humidity andtemperature are wanted, and in such cases the use of meteorologicalunits having the normallyopen-circuit contact assemblies of Figs. 18 and19 has the advantage that, since the meteorological measurements aretransmitted by short radio impulses, the amount of power required tooperate the radio transmitter is much less, and a material saving can beeffected in both the weight and cost of the batteries, which in turn isreilected in the size of balloon required and the amount of inilatinggas used. And, further, because of the reduction in weight of thebatteries, if the balloons used are of the same size as used for theinstruments having contact assemblies of the normally closed-circuittype, they may be inflated to a lower pressure and thereby enabled toreach greater heights before they burst.

It will be understood from the foregoing description that thetransmitter herein described, being made up of parts which areinterchangeable, has the advantage that the instrument is readilyrepairable in the field, and that identical meteorological measurementsare obtained with interchangeable unitary parts, a result not obtainablewith the instruments of the prior art. Further advantages of the newapparatus are, that no correction need be made of the measurementsrecorded as the result of the transmitted signals, the record beingdirectly 'in terms of pressure, humidity and temperature to be usedwithout the application of any corrective factors, so that the record ofa flight may be evaluated as received while the flight is in progress;that the apparatus as a whole is of comparatively rugged constructionand reliable in operation, and is made up of parts adapted for massproduction; and that the meteorological units are easily calibrated andadjusted, and are more accurate in their measurements than those of theprior art because of the play-free connections between the respondingelements and their contact assemblies, the use of levers, linkages,cords and pivots being largely eliminated, thereby removing theprincipal sources of error in the prior art instruments. Also, the newinstrument has a linear, or straight-line, characteristic, and may beadjusted to position its record on predetermined portions of the charton which its signals are recorded; and the meteorological units can havetheir response mcdied by intentional deforming of their operating camsto expand or reduce the scale of any desired portion of the measurementrange. For example, a radiobarograph transmitter used in conjunctionwith other apparatus for the study of cosmic rays might have itsoperating cam formed to produce precise and easily readable records of aballoons altitude at very low pressures even below 2O millibars.

It is, of course, to be understood that many parts or features of theinvention may be used independently of other parts and features and incombinations other than as shown and for other purposes. Themeteorological telemetering units are obviously adapted for independentuse. For example, the pressure unit might be used in apparatus carriedby small free balloons for determination of wind velocity and directionin conjunction with radio direction finding means, or used in connectionwith the study of cosmic rays.

The term instrument as used in the claims is not to be understood asimplying that the device so termed is a separately removable andreplaceable unit unless it is otherwise so dened in the claims.

What is claimed is:

l. In a, radiometeorograph transmitter, a meteorological transmitterwhich comprises a driving motor, a driving shaft driven by said motor, aplurality of telemetering transmitting instruments each having anelement responsive to u changes in an atmospheric condition and acontact assembly the position of which is controlled by said element anda rotary cam for coacting with said contact assembly, and drivingconnections between said shaft and the cam of each of said telemeteringinstruments, each of said telemetering instruments being a standardizedself-contained unit separately removable and replaceable and capable ofindependent adjustment and calibration.

2. In a radiometeorograph transmitter, a meteorological transmitterwhich comprises, a plurality of elements responsive to changes indifferent atmospheric conditions, a contact assembly comprising tworelatively movable members for each of said elements the position ofwhich as a whole is controlled by the element, a rotary cam foroperating each of said contact assemblies, a motor for driving saidcams, said cams being separately adjustable for adjustably varying theangular relation of the cams to each other, and means for separatelyadjusting each of said contact assemblies with relation to its operatingcam.

3. In a radiometeorograph transmitter, a meteorological transmitterwhich comprises, a plurality of elements responsive to changes indifferent atmospheric conditions, a contact assembly comprising tworelatively movable members for each of said elements the position ofwhich as a whole is controlled by the element, a rotary cam foroperatirg each of said contact assemblies, a motor for driving saidcams, and means for separately adjusting each of said contact assemblieswith relation to its operating cam.

4. In a radiometeorograph transmitter, a meteorological transmitterwhich comprises a cam, a driving motor therefor, an element responsiveto changes in an atmospheric condition, and a contact assemblycomprising two relatively movable members for coacting with said cam andthe position of which contact assembly as a whole with relation to thecam is controlled by said-element, the contact assembly and the elementbeing mounted for adjustment together for adjusting the contact assemblywith relation to the cam to vary the time of operation of the contactassembly.

5. In a radiometeorograph transmitter, a meteorological transmitterwhich comprises a cam, a driving motor therefor, an element responsiveto changes in an atmospheric condition, and a contact assemblycomprising two relatively movable members for coacting with said cam andthe position of ywhich contact assembly as a Whole with relation to thecam is controlled by said element, the contact assembly and the elementbeing mounted for .adjustment together for adjusting the contactassembly with relation to the cam to vary the time of operation of thecontact assembly, and the contact assembly and the element beingrelatively adjustable to vary the magnitude of movement imparted to thecontact assembly for a given change in said atmospheric condition.

6. In a radiometeorograph transmitter, a meteorological transmitterwhich comprises a cam. a driving motor therefor, an element responsiveto changes in said atmospheric condition, and a contact assemblycomprising two relatively movable members for coacting with said cam andthe position of which contact assembly as a whole with relation to thecam is controlled by said element, the contact assembly and the ele-

